JP2001304064A - Distributor type fuel injection pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce rigidity of a projecting part projecting to the face cam side from a cylinder end surface of a plunger of a distributed fuel injection pump. SOLUTION: A tapered part 61 having an outer diameter smaller than an untapered part 62 and absorbing whirling of a support object part 53 slidingly supported in a cylinder is arranged in the projecting part 54 of the plunger 9 of the distributed fuel injection pump to reduce the rigidity of the projecting part 54 of the plunger 9 even when lubricatability of gas oil reduces by high pressure of injection pressure of the distributed fuel injection pump and reduction in the sulfur content in the gas oil. Thus, even if the whirling of a drive shaft is transmitted to the plunger, the support object part 53 of the plunger 9 does not whirl though the projecting part 54 of the plunger 9 actively whirls. Thus, generating stress between the plunger 9 and the cylinder end surface is reduced to prevent seizure between the plunger 9 and the cylinder end surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distribution type fuel injection pump for distributing and supplying fuel to respective cylinders of an internal combustion engine such as a diesel engine.

[0002]

2. Description of the Related Art In recent years, exhaust gas regulations for diesel vehicles have been tightened worldwide, and fuel is distributed and supplied from a distribution type fuel injection pump to fuel injection nozzles provided for each cylinder of a diesel engine. Higher pressures and reductions in the sulfur content of light oil used as fuel for diesel vehicles are being carried out.

However, such an increase in the injection pressure and a reduction in the sulfur content in the gas oil result in an increase in the load (PV value) and a decrease in lubricity between the plunger and the cylinder. Due to the reduced lubrication of light oil, the alignment function of the drive shaft, coupling, and face cam is reduced, and the whirling of the drive shaft is transmitted to the plunger, causing a problem that the plunger whirls in the cylinder. I have. As a result, excessive stress is generated between the plunger and the cylinder end face, causing a problem of seizure between the plunger and the cylinder. Here, FIG.
FIG. 1 shows a burn-in portion in the prior art by a broken line.

On the other hand, as a conventional technique, Japanese Patent Laid-Open No.
In JP-A-54356, instead of lubrication with light oil, more lubricating engine lubricating oil is introduced into the distribution type fuel injection pump, and an engine lubricating oil flow path is formed on the outer peripheral portion of the plunger and the cylinder wall of the cylinder. There has been proposed a distribution type fuel injection pump having a structure for preventing seizure between a plunger and a cylinder end face by providing the same.

[0005]

However, in the conventional distribution type fuel injection pump, there is a problem that the engine lubricating oil staying in the engine lubricating oil passage tends to be heated to a high temperature, and it is difficult to obtain a desired lubricating property. Has occurred. Further, since it is necessary to provide an engine lubricating oil flow path on the outer peripheral portion of the plunger or to provide an engine lubricating oil flow path on the cylinder wall of the cylinder, the number of processing steps for the plunger and the cylinder is large,
The complicated formation of the engine lubricating oil flow path causes a problem that the manufacturing cost of the injection pump body (pump element) increases.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the rigidity of a protruding portion protruding from a cylinder end surface of a plunger toward a face cam side, and reduce the stress generated between the plunger and the cylinder end surface. The purpose is to prevent image sticking.

[0007]

According to the first aspect of the present invention, a supported portion slidably supported in the cylinder by a protruding portion protruding from the end face of the cylinder of the plunger to the face cam side. The rigidity of the protruding portion of the plunger is reduced by providing the absorbing portion for absorbing the whirling of the plunger. Thus, even if the whirling of the drive shaft is transmitted to the plunger, the supported portion of the plunger does not whirle, although the protruding portion of the plunger vibrates positively.

By reducing the stress generated between the end faces of the plunger and the cylinder, it is possible to reduce the number of processing steps for the plunger and the cylinder, thereby suppressing an increase in the manufacturing cost of the pump element, and to prevent the seizure between the end faces of the plunger and the cylinder. It can be reliably prevented. Therefore, the injection pressure of the fuel distributed and supplied to the fuel injection nozzles provided for each cylinder of the internal combustion engine from the distribution type fuel injection pump is increased, and the sulfur content of the fuel is reduced. Even if the load (PV value) increases and the lubricity decreases between the cylinders, seizure between the plunger and the cylinder end face can be prevented.

According to the second and third aspects of the present invention, the absorbing portion for absorbing the whirling of the supported portion of the plunger is a low-rigidity portion having lower rigidity than the supported portion, or With the small diameter portion having an outer diameter smaller than that of the support portion, even when the whirling of the drive shaft is transmitted to the plunger, the protruding portion of the plunger whirls, but the supported portion of the plunger does not wander.

According to the fourth aspect of the present invention, the absorbing portion for absorbing the whirling of the supported portion of the plunger has a smaller outer diameter than the non-tapered portion having a larger outer diameter than the supported portion. With the tapered portion provided so that the outer diameter gradually decreases from the end of the tapered portion toward the face cam, the same function and effect as the first aspect can be achieved.

According to the fifth aspect of the present invention, the absorbing portion for absorbing the whirling of the supported portion of the plunger has a smaller outer diameter than the non-tapered portion having a larger outer diameter than the supported portion. By providing the tapered portion so that the outer diameter gradually decreases from the end of the tapered portion toward the cylinder side, the same function and effect as the first aspect can be achieved.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described based on embodiments with reference to the drawings. First Embodiment FIGS. 1 to 5 show a first embodiment of the present invention. FIG. 1 shows a plunger of a distribution type fuel injection pump, and FIG. 2 shows a distribution type fuel injection pump. FIG. 3 is a view showing an overall structure of the fuel injection pump, and FIG. 3 is a view showing an electronic timer device of the distribution type fuel injection pump.

An electronically controlled distribution type fuel injection pump (hereinafter abbreviated as a distribution type fuel injection pump) of this embodiment has a drive shaft 2 rotatably housed in a pump housing 1 and a rotation of the drive shaft 2. A feed pump 3 which is connected to a drive shaft 2 via a coupling 4 and which reciprocates by a prescribed cam lift over a plurality of cam rollers 7 supported by a roller ring 6; 6 via a slide pin 40 for controlling the fuel injection timing in accordance with the fuel pressure in the pump chamber 20 (to be described later). And a pump element (discussed below) that pressurizes, distributes, and pumps.

The pump housing 1 includes a fuel temperature sensor 12 for detecting a fuel temperature in the pump chamber 20, a pump speed sensor 13 for detecting a rotation speed of the drive shaft 2, that is, a pump rotation speed, and a surplus fuel in the pump chamber 20. , A spill pressure valve (hereinafter referred to as SPV) 15 for controlling the fuel injection amount, a fuel pipe 16 for supplying fuel to the feed pump 3, a fuel injection pressure A plurality of constant pressure valves (hereinafter, referred to as CPV) 17 for controlling the pressure and a timer control valve (hereinafter, referred to as TCV) 18 for controlling the fuel injection timing are supported and fixed.

The SPV 15 is an electromagnetic actuator having an electromagnetic solenoid 19 whose energization is controlled by an engine control unit (ECU) (not shown). The SPV 15 is connected to the electromagnetic actuator via a drive rod, and is connected to an end of a pump element. A U-shaped spool 25 for changing the communication state of the fuel passages 21 to 24 for communicating the high-pressure chamber 50 and the pump chamber 20 formed in the pump, and a coil spring 26 for returning the spool 25 to the initial position. Spill valve.

The CPV 17 has discharge passages 30 to 33 communicating the distribution passage 29 and the fuel injection nozzles of the respective cylinders via the injection steel pipes, and always keeps the residual pressure of the fuel in the injection steel pipes constant. It is a constant residual pressure valve. TCV18
Is an electromagnetic solenoid (electromagnetic coil) 34 that is energized (for example, duty ratio controlled) by an engine control unit (ECU) (not shown), a valve body 35 that opens and closes a fuel introduction passage (not shown), and a valve body 35. A return spring 36 and the like for returning to the initial position are provided.

The drive shaft 2 is a rotating shaft driven by the rotation of the diesel engine to simultaneously drive the feed pump 3, the face cam 5, and the pump element. The drive shaft 2 is provided inside the cylindrical side wall of the pump housing 1 via a bush. It is supported rotatably. Further, a clearance C is provided at a connecting portion between the drive shaft 2 and the coupling 4, and the same applies to a connecting portion between the face cam 5 and the coupling 4. This prevents transmission of the whirling (movement direction B) of the drive shaft 2 rotationally driven by the crankshaft of the diesel engine to the face cam 5 and the plunger 9 connected to the face cam 5.

A rotary pulsar 37 on which a plurality of convex teeth are arranged is attached to the tip end side of the drive shaft 2. An electromagnetic pickup 39 of the pump rotational speed sensor 13 is attached to face the outer peripheral surface of the rotary pulsar 37. The feed pump 3 is built in the pump housing 1, pumps up fuel from a fuel tank (not shown), and sends the fuel into a pump chamber 20 formed in the pump housing 1.

The face cam 5 rotates in conjunction with the rotation of the drive shaft 2 and provides a reciprocating motion to the pump element simultaneously with the rotational motion. And
The face cams 5 have end cams in a number corresponding to the number of cylinders of the diesel engine along the circumferential direction. A plurality of metal cam rollers 7 held by a roller ring 6 connected to the electronic timer device via a slide pin 40 are in rolling contact with the end face cam. These cam rollers 7
Comes into contact with the end cam of the face cam 5, whereby the face cam 5 and the pump plunger 9 (hereinafter abbreviated as plunger) reciprocate a plurality of times during one rotation, that is, according to the number of cylinders of the diesel engine.

As shown in FIG. 2, the plurality of cam rollers 7 are rotatably supported by respective concave portions formed in the inner cylindrical portion 41 and the outer cylindrical portion 42 of the roller ring 6. The shaft 43 is rotatably supported on the end surface of the roller ring 6. Such cam rollers 7 are attached at predetermined intervals (for example, 90 ° intervals) in the circumferential direction of the roller ring 6 by the number facing the cam ridges of the face cam 5.

As shown in FIGS. 2 and 3, the electronic timer device includes a timer housing 44 integrally formed on the bottom side wall of the pump housing 1,
A timer piston 47 disposed so as to partition the inside of the timer cylinder formed by 4 into a timer high-pressure chamber 45 and a timer low-pressure chamber 46, and a timer spring 48 for urging the timer piston 47 in the direction of injection delay. It is configured. The timer housing 44 is formed of an aluminum alloy for weight reduction.

The timer piston 47 is incorporated in the timer housing 44 in a direction orthogonal to the drive shaft 2. The timer piston 47 is balanced by the fuel pressure of the pump chamber 20 in the pump housing 1 (pump internal pressure) and the load of the timer spring 48. The timer housing 44 is slidably housed in a timer cylinder. A cylindrical joint 49 is rotatably fitted into the timer piston 47, and the end of the slide pin 40 is connected to the joint 49.

The timer spring 48 applies a predetermined load to the timer piston 47.
4 is housed in a timer low-pressure chamber 46. The electronic timer device has a fuel introduction passage for introducing the fuel in the pump chamber 20 into the timer low-pressure chamber 46. A TCV 18 for controlling the fuel injection timing by adjusting the fuel pressure of the timer low-pressure chamber 46 by adjusting the opening degree is provided in the middle of the fuel introduction passage.

The pump element comprises a pump housing 1
A pump cylinder (hereinafter abbreviated as a cylinder) 8 press-fitted into a through hole provided in a side wall portion that liquid-tightly partitions the pump chamber 20 from the outside, and is slidably supported in the cylinder 8. A plunger 9 for reciprocating in the axial direction together with the rotational movement, a plunger spring 10 for pressing the plunger 9 against the face cam 5,
A head plug 11 is screwed into a through hole provided in a side wall of the pump housing 1 using a fastener such as a bolt. A high-pressure chamber (pressure chamber) 50 is formed between the inner peripheral surface of the cylinder 8, the end surface of the plunger 9, and the end surface of the head plug 11 to pressurize the sucked fuel to a high pressure.

The end face of the cylinder 8 on the face cam 5 side is open, and the end face on the side opposite to the face cam 5 side is closed by a head plug 11. This cylinder 8
The pump housing 1 is fitted in a through hole formed in a side wall portion of the pump housing 1 in a liquid-tight manner, and is formed in a substantially cylindrical shape. At the end of the cylinder 8, a suction port 5 that communicates the high-pressure chamber 50 with the pump chamber 20 (fuel passages 21 to 24) is provided.
1 is open. Further, at the center of the cylinder 8, a distribution port 52 communicating with each CPV 17 via each distribution passage 29 provided in the same number as the number of cylinders of the diesel engine is opened.

The plunger 9 is formed in a substantially round bar shape (substantially cylindrical shape), and is driven by a face cam 5 connected to the drive shaft 2 by a coupling 4.
It is pressed against the face cam 5 by the plunger spring 10. The plunger 9 connected to the face cam 5 that reciprocates on the plurality of cam rollers 7 held by the roller ring 6 by a predetermined cam lift,
It reciprocates while rotating, and after dispensing fuel, performs distribution pumping.

The plunger 9 is fitted into the cylinder 8 with one end on the face cam 5 side protruding from one end surface (inner wall surface) of the cylinder 8. That is, as shown in FIGS. 1 and 2, the plunger 9 includes a portion (supported portion) 53 slidably supported on the inner peripheral surface (sliding surface) of the cylinder 8 and the end surface of the cylinder 8. A portion (projection) 54 projecting toward the face cam 5 is provided. The supported portion 53 is slidably supported on the inner peripheral surface of the cylinder 8 with a predetermined clearance with respect to the inner diameter of the cylinder 8. A communication passage 55 is formed inside the supported portion 53, and a distribution groove 56 and a pressure equalizing groove 57 are formed on the outer peripheral surface of the supported portion 53.

An outermost diameter portion (fitting portion) 59 that is fitted to the face cam 5 using a fixing pin 58 from the face cam 5 side to the end face side of the cylinder 8 from the face cam 5 side to the protruding portion 54. The disk portion 60 having a small outer diameter, and the absorbing portion (tapered portion) 6 having a smaller outer diameter than the disk portion 60.
1. A large diameter portion (non-tapered portion) 62 having an outer diameter larger than the tapered portion 61, a groove portion 63 having an outer diameter smaller than the non-tapered portion 62, and the like are provided. An adjustment shim 64 is mounted between the fitting portion 59 and the face cam 5.

The tapered portion 61 reduces the rigidity of the protruding portion 54 of the plunger 9 so that even if the whirling of the drive shaft 2 is transmitted to the plunger 9, the protruding portion 54 of the plunger 9 actively whirls, and The support portion 53 is a portion that does not swing, and in this embodiment, is formed in a tapered shape in which the outer diameter gradually decreases from the non-tapered portion 62 toward the disk portion 60.

The tapered shape of the tapered portion 61 is such that the dimension from the end face of the disk portion 60 to the end face of the non-tapered portion 62 is a (22.1 mm in this example),
30% when the dimension of 1 is b (7.8 mm in this example)
４０40%, desirably 35%. Also,
The minimum outer diameter of the tapered portion 61 is φc, and the non-tapered portion 6
When the outer diameter of No. 2 is φd (φ11.13 mm in this example), φc = φd−2.5 (mm).

One end of the non-tapered portion 62 is connected to the tapered portion 61, and the other end is hooked on one end surface of the cylinder 8 when the plunger 9 is assembled in the cylinder 8. That is, the outside diameter of the other end of the non-tapered portion 62 is larger than the inside diameter of the cylinder 8. Thus, when the supported portion 53 of the plunger 9 is assembled in the cylinder 8 and the face cam 5 and the plunger 9 are assembled in a state where the opening on the other end side of the cylinder 8 is not closed by the head plug 11, 9 can be prevented from falling into the cylinder 8 up to the protrusion 54.

The plunger spring 10 is a plunger biasing means for biasing the fitting portion 59 of the plunger 9 in a direction of pressing the face cam 5, and is disposed around the spring guide 70, and has one end connected to the lower spring seat 71. The other end is held by the upper spring seat 72. The lower spring seat 71 is connected to the plunger 9 via the upper plate 73 and the lower plate 74.
Is connected to the fitting part 59 of

[Operation of the First Embodiment] Next, the operation of the distribution type fuel injection pump of this embodiment will be briefly described with reference to FIGS.

A) Suction stroke The rotation of the drive shaft 2 causes the face cam 5 to rotate, and the plunger 9, which is given a rotary motion and a reciprocating motion in accordance with the rotation of the face cam 5, moves downward (FIG. 2).
At the left in the figure) and the SPV 15 is EC
U is energized to open the valve. That is, the pump chamber 20 into which fuel is pumped from the fuel tank by the feed pump 3 and the high-pressure chamber 50 are connected to the fuel passage 21.
Through 24 are connected.

Therefore, the fuel in the pump chamber 20 communicates with the suction port 51 formed in the cylinder 8 and the high-pressure chamber 50, so that the pump chamber 20 → the fuel passage 21 → the fuel passage 22 → the fuel passage 23 → Fuel passage 24 → suction port 5
Through 1, the air is sucked into the high-pressure chamber 50 surrounded by the inner peripheral surface of the cylinder 8, the head end surface of the plunger 9, and the end surface of the head plug 11, and the communication passage 55 inside the plunger 9.

(B) Distribution and pressure-feeding process When the plunger 9 rotates, the ECU controls the SPV.
The energization to 15 is stopped and the valve is closed, and the distribution groove 56 of the plunger 9 is opened to one distribution port 52 of the cylinder 8. When the plunger 9 further rotates,
The face cam 5 rides on the cam roller 7 rotatably supported by the roller ring 6, and the plunger 9 starts to move rightward in FIG. 2 to reduce the volume of the high-pressure chamber 50, and at the same time to distribute and pump fuel. Be started.

As the fuel pressure in the communication passage 55 inside the high-pressure chamber 50 and the plunger 9 increases, C
The PV 17 compresses and lifts the valve spring. For this reason, the high-pressure fuel pressurized by the reduction of the volume of the high-pressure chamber 50 is supplied to the communication passage 55 inside the plunger 9.
→ distribution groove 56 → distribution port 52 → distribution passage 29 →
Discharge passage 30 of CPV 17 → discharge passage 31 → discharge passage 3
2 → discharge passage 33 → injection into the combustion chamber of the diesel engine via the injection steel pipe from the fuel injection nozzle corresponding to the injection steel pipe among a plurality of fuel injection nozzles attached to each cylinder of the diesel engine.

(C) End of injection When the plunger 9 is further moved rightward in FIG. 2 by the cam roller 7 of the roller ring 6, energization of the SPV 15 is started again by the ECU and the valve is opened. Accordingly, the high-pressure fuel in the high-pressure chamber 50 and the communication passage 55 inside the plunger 9 is supplied to the suction port 51 → the fuel passage 24 →
The fuel is pushed back into the fuel passage 23 → the fuel passage 22 → the fuel passage 21 → the pump chamber 20, the pressure in the distribution passage 29 is reduced, and the pumping of the fuel is terminated, and the injection from the fuel injection nozzle is terminated.

D) Equalizing stroke When the plunger 9 is further rotated by 180 °, the equalizing groove 57 of the plunger 9 is fitted with one distribution port 52 of the cylinder 8, and the fuel pressure in the distribution passage 29 is reduced by the pump chamber 20.
Asymmetric injection is prevented by making the fuel pressure equal to the internal fuel pressure.

E) Injection timing adjustment The fuel injection timing is determined at the point where the plunger 9 starts to rise, that is, at the time of starting the pressure feeding. The pressure feeding start timing is a point at which the face cam 5 starts to rise on the cam roller 7 rotatably supported by the roller ring 6. Therefore, if the position of the cam roller 7 is changed, the fuel injection timing can be changed. .

The position of the cam roller 7 is controlled by controlling the position of a timer piston 47 of an electronic timer incorporated in the distribution type fuel injection pump. That is, in the present embodiment, the fuel in the pump chamber 20 of the pump housing 1 is introduced into the timer high-pressure chamber 45 of the timer housing 44 as described above. As a result, the timer piston 47 is incorporated in the timer housing 44 in a direction orthogonal to the drive shaft 2, and the timer piston 47 moves inside the timer housing 44 by the balance between the pump internal pressure (the fuel pressure of the pump chamber 20) and the load of the timer spring 48. Slide. Further, the movement of the timer piston 47 is changed to a movement of rotating the roller ring 6 holding the cam roller 7 via the slide pin 40. The pump internal pressure applied to the timer high-pressure chamber 45 at one end of the timer piston 47 increases as the pump rotation speed increases and the feed hydraulic pressure of the feed pump 3 increases.

Accordingly, when the pump rotation speed increases and the pump internal pressure increases, the timer piston 47 is advanced (to the left in FIG. 3) while pressing and contracting the timer spring 48 against the urging force of the timer spring 48. , And the roller ring 6 is rotated in the direction opposite to the rotation direction of the drive shaft 2 to advance the fuel injection timing.

Here, in this embodiment, the fuel in the pump chamber 20 of the pump housing 1 is introduced into the timer low-pressure chamber 46 of the timer housing 44 through the fuel introduction passage via the TCV 18 as described above. . As a result, the fuel in the pump chamber 20 of the pump housing 1 is transferred to the TCV 18
To the timer low-pressure chamber 46 through the control of the TCV 18, for example, by opening and closing the TCV 18 according to the engine load to adjust the timer low-pressure chamber pressure (fuel pressure of the timer low-pressure chamber 46)
The fuel injection timing can be controlled by restricting or permitting the movement of the timer piston 47 to the advance side.

[Features of the First Embodiment] As described above, in the distribution type fuel injection pump of the present embodiment, the clearance C is provided at the connecting portion between the drive shaft 2 and the coupling 4 and the face The same applies to the connection between the cam 5 and the coupling 4. This prevents transmission of the whirling (movement direction B) of the drive shaft 2 rotationally driven by the crankshaft of the diesel engine to the face cam 5 and the plunger 9 connected to the face cam 5.

However, an increase in the driving torque due to an increase in the injection pressure of the fuel and a decrease in the lubricity of the light oil cause
If the sliding of the connecting portion between the drive shaft 2 and the coupling 4 and the connecting portion between the face cam 5 and the coupling 4 is deteriorated, the whirling of the drive shaft 2 may be transmitted to the plunger 9. . This allows
As shown by the broken line (conventional example) in the graph of FIG. 4, the generated stress between the plunger 9 and the end face of the cylinder 8 increases, and as shown in the graph of FIG. There was a problem that it would. In addition,
In FIG. 2, the burn-in portion in the case of the conventional technique is indicated by a broken line.

Therefore, in the present embodiment, the rigidity of the protruding portion 54 is reduced by providing the tapered portion 61 at a portion (protruding portion) 54 protruding from the end surface of the cylinder 8 of the plunger 9 toward the face cam 5. Even if the whirling of the drive shaft 2 is transmitted to the plunger 9, the projecting portion 54 actively whirls, and the portion (supported portion) 53 slidably supported on the inner peripheral surface of the cylinder 8 does not whirling. . Thereby, the generated stress between the plunger 9 and the end face of the cylinder 8 can be reduced, and the seizure between the plunger 9 and the end face of the cylinder 8 can be prevented.

Next, the effect of reducing the load (PV value) between the plunger 9 and the end face of the cylinder 8 by the distribution type fuel injection pump having the structure of this embodiment is shown in the graph of FIG. This figure 4
According to the graph, the load (PV value) between the plunger 9 and the end face of the cylinder 8 in the distribution type fuel injection pump (invention product) having the structure of this embodiment is 5.81 × 10
⁴ (N / mm · s) from ^{5.04 × 10 4 (N / mm} ·
s).

In the distribution type fuel injection pump (invention) having the structure of this embodiment, the high pressure chamber 50 with the seizure limit is not used.
Of the distribution type fuel injection pump (invention) having the structure of the present embodiment whose pressure is improved by 30 MPa or more, even if the lubricating property is reduced by increasing the injection pressure, the distance between the plunger 9 and the end face of the cylinder 8 is reduced. Can be prevented from burning.

[Second Embodiment] FIG. 6 shows a second embodiment of the present invention and is a view showing a plunger of a distribution type fuel injection pump.

The plunger 9 of this embodiment has a portion (projecting portion) projecting from the end face of the cylinder 8 to the face cam 5 side.
54 is provided with a tapered portion 61 on the cylinder 8 side.
The tapered shape of the tapered portion 61 is 35% (a / b = 0.35) of the non-tapered portion 62, and the minimum outer diameter φc of the tapered portion 61 is (the outer diameter φ of the non-tapered portion 62).
d-2.5 mm).

Thus, also in this embodiment, the protrusion 54
The rigidity of the drive shaft 2 is reduced, and even if the whirling of the drive shaft 2 is transmitted to the plunger 9, the non-tapered portion 62 actively whirls and is slidably supported on the inner peripheral surface of the cylinder 8 (the portion to be slidable). The support portion 53 does not swing. Thereby, the generated stress between the plunger 9 and the end face of the cylinder 8 can be reduced, so that the seizure between the end face of the plunger 9 and the cylinder 8 can be prevented.

[Modification] In this embodiment, the outer diameter of the non-tapered portion 62 is larger than that of the non-tapered portion 62 as an absorbing portion for absorbing the whirling of the supported portion 53 slidably supported in the cylinder 8 of the plunger 9. An end surface of the cylinder 8 may be provided with a tapered portion 61 provided so that the outer diameter gradually decreases from the end of the non-tapered portion 62 toward the face cam 5 side. Although the tapered portion 61 provided so that the outer diameter gradually decreases toward the side is provided, the absorbing portion may be a low-rigidity portion having lower rigidity than the supported portion 53. It is good also as a small diameter part whose outer diameter is smaller than that. Further, the weight of the protruding portion 54 may be reduced in weight than the supported portion 53 of the plunger 9. Further, the supported portion 53 and the projecting portion 54 of the plunger 9
May be made different from each other so that the rigidity of the protruding portion 54 is lower than that of the supported portion 53.

In this embodiment, an example in which the present invention is applied to a distribution type fuel injection pump having an electronic timer device of a timer low pressure chamber pressure control type has been described. May be used for a distribution type fuel injection pump provided with the electronic timer device. Further, the present invention may be applied not only to an electronic timer device having a TCV but also to a mechanical ordinary hydraulic timer device having no TCV.

[Brief description of the drawings]

FIG. 1 is a side view showing a plunger of a distribution type fuel injection pump (first embodiment).

FIG. 2 is a cross-sectional view showing the entire configuration of the distribution type fuel injection pump (first embodiment).

FIG. 3 is a sectional view taken along line AA of FIG. 2 (first embodiment);

FIG. 4 is a graph showing a stress generated between a plunger and a cylinder end face with respect to a sliding speed of a plunger of the distribution type fuel injection pump (first embodiment).

FIG. 5 is a graph showing the pressure in the high-pressure chamber of the cylinder with respect to the pump rotation speed of the distribution-type fuel injection pump (first example).
Example).

FIG. 6 is a side view showing a plunger of the distribution type fuel injection pump (second embodiment).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pump housing 2 Drive shaft 3 Feed pump 4 Coupling 5 Face cam 6 Roller ring 7 Cam roller 8 Cylinder 9 Plunger 10 Plunger spring 11 Head plug 20 Pump chamber 40 Slide pin 50 High pressure chamber 53 Supported part 54 Projection part 61 Tapered part (Absorbing part) 62 Non-tapered part (large diameter part)

Claims (5)

[Claims] A drive shaft rotatably driven by an internal combustion engine, a face cam connected to the drive shaft via a coupling and reciprocating on a fixed roller by a predetermined cam lift, and a face cam side. A cylindrical cylinder having an open end face and having a high-pressure chamber formed therein is connected to the face cam, and rotates and reciprocates in the cylinder to add fuel sucked into the high-pressure chamber. A dispensing type fuel injection pump comprising: a plunger that performs pressure feeding by pressure; wherein the plunger has a supported portion slidably supported in the cylinder, and a plunger projecting from the end face of the cylinder toward the face cam. A protrusion that is provided, and the protrusion is provided with an absorbing portion that absorbs whirling of the supported portion. Distribution type fuel injection pump. 2. The distribution type fuel injection pump according to claim 1, wherein the absorption section is a low rigidity section having lower rigidity than the supported section. 3. The distribution type fuel injection pump according to claim 1, wherein the absorption section is a small diameter section having an outer diameter smaller than that of the supported section. pump. 4. The distribution type fuel injection pump according to claim 1, wherein the absorbing portion has an outer diameter larger than that of the non-tapered portion having an outer diameter larger than that of the supported portion. A distribution type fuel injection pump, characterized in that the distribution type fuel injection pump is a small, tapered portion provided so that the outer diameter gradually decreases from the end of the non-tapered portion toward the face cam. 5. The distribution type fuel injection pump according to claim 1, wherein the absorbing portion has an outer diameter larger than that of the non-tapered portion having an outer diameter larger than that of the supported portion. A distribution type fuel injection pump, wherein the distribution type fuel injection pump is a small tapered portion provided so that the outer diameter gradually decreases from the end of the non-tapered portion toward the cylinder side.